Telephone-exchange system



2 Sheets-Sheet 1.

(No Model.)

0. E. SORIBNER.

TELEPHONE EXGHANGE SYSTEM.

N0. 891,762. Patented Oct. 23, 1888.

N. PETERS. PholoLRhograpMr. Wath nglcn. D, (L

' 2 Sheets-Sheet 2.

(No Model.)

0. E. SORIBNEB. TELEPHONE EXCHANGE SYSTEM.

Patented Oct 23, 1888 {lm F flw/evafir. 7 Q5464 a/MM 11, PEIERS. mwmm w. Washington. me.

NITED STATES PATENT CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS.

TELEPHONE-EXCHANGE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 391,762, dated October 23, 1888.

Application filed June 6, 1881.

To all whom it may concern.-

Be it known that 1, CHARLES E. SORIBNER,

. a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful ImprovementinTelephoneExchangeSystems, (Case 27,) of which the followingisa ful1,clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to that system of telephone-exchange in which the subscribers telephone-lines are grouped or connected through a common line at the central office, in which is placed a telephone. The operator stands listening at this telephone, and is thus always ready to answer asubscriber. Thesubscriber hasonl y to take down his telephone and speak directly into his transmitter. The subscribers soon learn not to interfere with one another, since each can hear the conversation that is going on between the operator and any other subscriber.

Heretofore the common wire has been grounded at the central office, and the outer ends of the wires have been connected to a common line, as will be seen by reference to my patent, No. 266,321, granted October 24-, 1882, for telephone-exchange system, applica tion filed March 22,1881. Where, say,twentyfive telephone-lines are thus connected to a common ground-wire at the central office, it is evident that if, for example, four subscribers should have their telephones down and should be in connection with the listening operator there would be five groundconnections--one at the central office and one at each of the four subscribers stations. Therefore the voice-current sent from any one of those stations would be divided and pass to ground in derived circuit at four other ground points. The number of subscribers, therefore, which may be advantageously included in a single group is limited. If, however, the common wire at the central office, instead of passing to ground, is connected with a second group of telephone-lines, it is evident that when two subscribers of opposite groups take down their telephones a closed circuit will be formed from their grounds through the listening operators telephone, included in the common wire at the central office, and thus the voice-current Serial No. 35.037. {No model.)

sent from either subscribers station through the common wire will not be weakened by reason of a ground being formed at the station of any subscriber of the opposite group. On the other hand, in case all the telephones of one group are hung up so that there is'no ground-connection with said group telephonic communication may be maintained between any subscriber of the other group and the listening operator, since the first group, when disconnected from the ground, acts as one plate of a condenser.

My invention consists in the method of operating telephone-exchanges,whereby the eondenser capacity of two groups thus connected to the opposite ends of a common wire is taken advantage of to enable any subscriber of one group to communicate with the listening. operator having his telephone included in said common wire.

My invention also consists in grouping the subscribers lines on opposing sides of the wire containing the listening operators telephone outfit,and thereby dispensing with the groundconnection at the central office.

My invention is illustrated in the acconr panying drawings, in which- Figure 1 is a diagram illustrative of my invention. Fig. 2 is a View of the same somewhat in detail.

Like parts are indicated by similar letters of reference throughout the different figures.

Referring now to Fig. 1, it will be seen that there are two groups of telephone-lines 0on5 nected with the same switch-board at the central office and thence to a common line, including the operator s telephone The telephone-lines of the stations 1, 2, 3, and 4 con stitute group A, and the telephone-lines of stations 5, 6, 7, and 8 constitute group B. There may be in practice, say, from twenty to twentyfive lines in each group. At station 8 I have shown a subscribers outfit consisting of telephone c, switch I), and bell c. Any other subscribers outfit may be used at the different subscribers stations. The outer ends of the telephone-lines of group A are connected with the common line (1, while the outer ends of the telephone-lines of group B are connected by the common line f. There are normally no ground-connections except when the subscribers remove their telephones from the switches.

When a telephone is thus removed from a switch, as shown at station 8, the telephone-line 0 will be disconnected from the bell c and the common linef and closed to ground, as shown through the switch I) at said station. The subscriber on thus taking down his telephone may speak at once to the operator listening at tele' phone g, the condenser capacity of group A being sufficient to allow the voicecurrent sent from station 8 to operate the telephone 9, although there may be no ground whatsoever upon group A. Suppose subscriber 8 asks for subscriber 2. The operator, on being informed of the connection desired, by inserting plug h in switch 2 sends current from the negative pole of battery 1' over line 70, through bell lat station 2. The current, after passing through said bell, finds circuit back to the positive pole of the battery by common line d, and such telephone-lines of group A as happen at the time to be connected with said common line. The current after passing through said bell Z, being distributed through several different telephone-lines, will not be strong enough in any one line to ring the bell included therein. As described in my said patent, the bells may be polarized, if desired, so as to respond to current in but one direction. Subscriber 2 will thus be notified by the ringing of his bell and will at once take down his telephone from the switch, and thereupon the switch will antomatically assume the position shown at station 2 in Fig. 2. Line 76 will thus be disconnected from the common line d and closed to ground through the telephone at station 2, as shown. The plug h is then removed and subscribers 8 and 2 may then be connected together by aflexible cord provided with terminal plugs, as shown upon the switch-board at the central office in Fig. 2. Any two subscribers, whether of the same or opposite groups, may thus be connected together. Lines when thus in use are cutoff from the listening operators telephone. A clearingout drop may be included in the circuit of the connecting-cord in the usual manner. Lines in use, therefore, are thus insulated from the other lines of the system. If, however, several subscribers take down their telephones at the same time to speak to the listening operator, there will be a groundconnection established at each station of the subscribers who are thus asking for connection; but as the lines are distributed in groups on different sides of the telephone 9 it will in practice never happen that so many lines of one group will be grounded as to interfere with the successful working of the system.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- 1. In a telephone exchange system, the combination, with two groups of telephonelines, of a telephone placed in a line between said groups, a common line connecting the outer ends of each of said groups, and switching apparatus at the different subscribers stations, whereby any telephone-line may be disconnected from the outer line of its group and con nected to ground to form a circuit through the telephone at the central office.

2. In a telephone-exchange, the combination, with two groups of telephone-lines, each group being normally connected with a different outer common line, of a telephone outfit at the central office included in a line connecting said groups and switching apparatus and telephones at the different subscribers stations, whereby any telephone-line may be closed to ground at the subscribers station located thereon and telephonic communication established between the subscriber at said station and the operator at the central office.

8. The combination, with a group of telephone-lines disconnected from the ground, of a telephone-line connected with said group through a telephone at the central office and through a subscribers telephone outfit at the subscribers station on the line, whereby telephonic communication may be maintained between the subscribers said station and the central office.

4. A telephone-circuit including two telephones located at different stations, one end of said circuit being connected with the ground and extending from said ground throughboth of the telephones, the portion of said circuit beyond said telephones being disconnected from the ground, but of sufficient extent to act as one plate of a condenser, whereby communication may be maintained between the said telephones.

5. In a telephone-exchange system, the combination, with two groups of telephone-lines connected at the central office on different sides with the same telephone, of outer common lines, one for each group, said outer common lines being disconnected from the ground, bells at the different subscribers stations, one in each telephone-line, and a battery and switching apparatus at the central office, whereby current may be sent out over any one of said telephone-lines to ring the bell at the station on said line.

IIO

6. Telephone-lines radiating at the central office from the different sides of a telephone to subscribers stations, the telephone-lines on each side of the central-office telephone being normally connected with a common line and disconnected from ground, and a subscribers telephone outfit at each station, whereby any subscriber may disconnect from the common outer line and close his line to ground by the act of removing his telephone from its support to speak with the listening operator.

7. In a telephone-exchange, telephone-lines radiating from the central office to different subscribers stations, a switch-board at the central office provided with switches, one for each telephone-line, a wire at the central office including a listening operators'telephone, the telephone-lines after passing through their respective switches being connected in groups on different sides of said operators telephone, the different groups of wires being connected at their outer ends with a common line, a subscribers telephone outfit at each of the subscribers stations and switching apparatus at the central office, whereby any two telephonelines may be connected together and insulated from the other telephone-lines of the system.

8. The telephone at the central office in a loop between two groups of telephone-lines, several of the lines of each group being grounded at the subscribers stations thereon, whereby any of said several subscribers may communicate with the listening operator.

9. The combination, with telephone-lines radiating from a central office to subscribers stations and provided with subscribers telephone outfit-s at the different stations, of a telephone included in a loop connecting the two groups of said lines, whereby any subscriber in either group may communicate with the operator at said telephone.

10. The combination, with a telephone and telephone-lines connected with opposite sides of said telephone, the said telephone-lines ex tending to subscribers stations and being provided at the different subscribers stations with a telephone, telephone-switch, and a bell, of a battery and switching apparatus at the central station, whereby signals may be sent from the central station to any subscribers station, substantially as described.

11. A telephone included in a loop at the central station, the opposite-ends of said loop being connected each with a different group of telephone-lines, each subscribers line being provided with a telephone in a ground-circuit and a switch, whereby any subscriber may close his line through his telephone to ground and communicate with the operator at the telephone in the loop, the telephone-lines of the different groups when not in use serving 40 as condensers.

CHARLES E. SORIBNER.

WVitnesses:

WM. S. GRANGER, GEO. P. BARTON. 

